1. Field of the Invention
The present invention relates to a fishing net for use in capturing fish concentrated in an area near the surface of a body of water.
2. Description of the Prior Art
In conventional commercial fishing techniques, it has traditionally been a practice for fishing personnel aboard a commercial fishing boat to capture a school of fish in an ocean utilizing a purse net, sometimes called a seine fishing net. A purse seine fishing net is a net shaped generally in the form of a mesh curtain having a rope or line extending along the top edge and provided with spaced floats, such as corks. This upper line is commonly known as the "cork line". The bottom edge of the seine fishing net is weighted so that it extends vertically downwardly from the surface of the water to stretch the seine net to its maximum vertical length. A purse line is also located along the bottom edge of the net. The lower portion of the netting is known as the pursing apron.
In the use of a conventional seine pursing net, a school of fish is first located in the ocean and an ocean fishing vessel motors to the location of a school of fish. A motor boat is deployed to encircle the school of fish while continuously dropping portions of the seine fishing net overboard. The motor boat returns to its original starting location to establish proximate contact with a skiff that has remained at the initial end of the seine net. Upon establishing such contact, the seine net forms a generally cylindrical mesh curtain. A net functioning as a "sack", at the lower end of the netting is utilized to gather together the captured school of fish. The fish are removed from the sack and transferred into the hold of the motor boat.
The foregoing traditional activity involves a considerable expenditure of labor and time-consuming maneuvers about and within the school of fish. In some cases, many of the fish escape prior to sacking. Also, considerable time is expended from the initial sighting of the fish until deployment of seine purse net. In addition, during the sacking process, the purse seine net is collapsed. This results in the killing of certain species of fish that would otherwise be released and the death of entrapped sea mammals, such as porpoises, as well.
As an advance in the art an alternative solution was devised to produce a noncollapsible deep sea fishing net which is deployed by helicopter. This system is described in U.S. Pat. No. 4,986,021, which is incorporated herein by reference in its entirety.
According to the '021 patent, a fishing net is constructed generally in the shape of a cylinder having an open top and, initially, an open bottom. A buoyant float ring is connected to the generally circular top edge of the net while a weighted ring is connected approximately two-thirds of the way down the vertical length of the net, thus leaving a weighted skirt extending therebeneath. A draw line provided around the lower edge of the skirt is weighted with a closure weight. The closure weight is connected to the draw line, but is initially suspended from above by a cable from a helicopter hovering overhead. Once the net has been deployed in the water and the weight ring has sunk to the desired depth, the school of fish is laterally encircled beneath the surface of the water by the cylindrical net suspended from the buoyant float ring. Personnel in the helicopter then release the closure weight, which thus pulls on the draw line and closes the bottom of the skirt so that the fish cannot dive beneath the lower edge of the net and escape.
The device of the '021 patent has significant advantages over conventional seine purse fishing nets. It can be deployed rapidly by helicopter and positioned so as to laterally encircle a school of fish before the fish can escape. Once the bottom of the skirt has been closed, the fish are entrapped within the lateral confines of the net, and cannot escape through the bottom of the net, since the skirt has been closed. Moreover, both the float ring and the weight ring retain their original geometric shape, thus preventing the net from collapsing. As a consequence, although the fish are entrapped within the net, they are not likely to be killed since the net retains its shape and in effect forms a floating cage or aquarium. This allows the fishing vessel sufficient time to reach the site of capture whereupon the fishing vessel personnel use a crane to slowly raise the drop net.
As the drop net is raised, the fish swim to the surface and through a special "chute" into another holding net attached to the ship. Unwanted and protected species are returned to the sea. Because the netted fish are alive, they are suitable for aquarium use, sea farming, tag and release, and other manner of uses that require live, uninjured delivery. Moreover, because the drop net of the '021 patent can be deployed by helicopter, it can be dropped from above upon a concentration of a school of fish which often feed close together at the surface of the sea in a frenzied condition. A school of fish engaged in such frenzied feeding produce a recognizable water condition known in the fishing industry as "foaming" or "boiling" which can be visually spotted from the air a considerable distance away.
One significant problem with the drop net disclosed in the '021 patent which has persisted, however, is the closure or pursing arrangement. It is extremely difficult for personnel aboard a helicopter to properly control the closure weight at a correct time that will maximize capture of the fish. In deploying the drop net, all too often the closure weight is dropped either too early or too late. When the weight is dropped too early, the skirt of the net is closed above a major portion of the school of fish, thus allowing those fish to escape. Conversely, if the closure weight is dropped too late, a large portion of the school of fish escape from the lateral confines of the net merely by diving beneath the lower edge of the skirt and swimming away before the skirt can be closed. Thus, while the drop net of the '021 patent does represent a significant theoretical advance in the fishing industry, the difficulty in closing or pursing the net has remained an unsolved practical problem that has persisted for a number of years.